A Blueprint for Ultra-Fast DOCSIS6/18/2012 12:01 AM Eastern
Do cable operators need to build out pricey
fiber-to-the-home networks to keep pace with crushing
data demand over the next decade?
Perish the thought.
That’s according to a research paper, co-authored by
Arris Group, Cisco Systems, Motorola Mobility and Intel,
which makes specific recommendations for “DOCSIS NG,”
envisioned as a next-generation version of the cable industry’s
broadband technology platform.
With certain fundamental changes, DOCSIS could
deliver as much as 10 Gigabits per second of bandwidth
downstream and perhaps 2 Gbps upstream, according to
the paper. And, ideally, that gigantic pipe should satisfy
the thirst for higher-speed Internet for years to come.
“There’s almost been a sigh of relief to know that we
can go forward with DOCSIS for a long, long time,” John
Chapman, chief technology officer for Cisco’s Cable Access
Business and an engineering fellow, said. “There was
an open question of how far we could push DOCSIS 3.0.”
The vendors presented the paper, “Mission Is Possible:
An Evolutionary Approach to Gigabit-Class DOCSIS,” at
the 2012 Cable Show last month.
Now, the ball is in CableLabs’ court as far as what it
takes — or leaves — from the recommendations.
Asked for comment, the operator-owned R&D consortium
said, “CableLabs continually considers input from
multiple sources as it evaluates how future technologies
may benefit its members.”
CableLabs has already been quietly exploring what the
next generation of cable broadband may look like, including
an approach that would eliminate 6-MHz channel divisions
(see “Monster Bandwidth,” April 26, 2010).
DOCSIS 3.0 provides suitable runway for at least the
next three years, able to deliver nearly 1 Gbps downstream
and up to 300 Megabits per second upstream, according to
Chapman, who was one of the paper’s authors. But the industry
needs to plan now for where DOCSIS is headed beyond
that horizon, he said.
The DOCSIS NG research was driven in large part by
the IEEE’s proposed Ethernet Passive Optical Network
Protocol over Coax (EPOC) spec, designed to deliver symmetrical
10 Gbps speeds over existing last-mile coax — potentially
“EPOC helped legitimize the market to show there was
an appetite for higher-bandwidth technologies,” Chapman
said. “We said, ‘Let’s prove we can do a Gigabit in the upstream
with DOCSIS.’ ”
Regardless of what “DOCSIS 4.0” ends up looking
like, a major challenge for MSOs will be freeing up
channels on the plant to provide the spectrum to hit
multigigabit speeds, according to Tom Cloonan, chief
technology officer of Arris’s network-solutions group.
“The technology supports it. Now we just have to find room
for it,” he said.
Key suggestions among 10 recommendations
made by four cable tech vendors for “DOCSIS NG”:
Expand HFC plant spectrum to 1.7 GHz,
enabling downstream bandwidth of up to
10 Gigabit per second.
Use “high split” of 5-230 MHz (or even up to
400 MHz) for upstream path, allowing speeds of
1 Gbps or more.
Replace DOCSIS’s physical (PHY) layer with
orthogonal frequency-division multiplexing (OFDM)
using low density parity-check (LDPC) forward
Enable higher-order modulations of 4096-
QAM or more.
Ensure “co-existence” with current DOCSIS cable
modems to be able to use the same spectrum.
SOURCE: Vendor research paper